We plan to determine the chromatin fine structure of genes (Drosophila melanogaster ribosomal RNA genes, 6S RNA genes, histone genes and alcohol dehydrogenase gene; sea urchin 'early' and 'late' histon genes). In particular, we will map the position of a) nucleosomes at and near those gene DNA sequences and b) exposed DNase 1 hypersensitive sites. Once the chromatin 'anatomy' of these genes is define, we shall monitor the (probable) changes in chromatin structure during development. We will prepare specific DNA subclones from those genes (carrying only spacer DNA sequences, gene DNA sequences or the DNase 1 hypersensitive sequences) in order to a) search for an characterize DNA sequence-specific non-histone chromosomal protein and b) probe and analyse fractionated nucleoprotein particles carrying either transcribed gene DNA sequences or non-transcribed spacer DNA sequences. Reconstitution studies will be performend with pure Deosophila histones and non-histone proteins on cloned Drosophila DNAs, to determine the requirements for a proper alignment of nucleosomes on the DNA sequence.